Orbit Airlines Flight 112
Orbit Airlines Flight 112 was a scheduled transcontinental passenger flight from McCarran International Airport in Las Vegas, Nevada, to London Heathrow International Airport in London, England. On September 16, 2008, while flying over Texas, the Boeing 747-400 operating the flight suffered a catastrophic engine failure in the inboard port (number 2) engine. This failure caused small fragments of engine debris to be hurled into the outboard port (number 1) engine and into the plane's fuselage and wing, causing a rapid decompression and damaging several fuel systems, as well as causing an undetected engine fire in the number 2 engine that eventually self-extinguished. Despite the loss of the two engines and damage to the plane itself, the flight was able to successfully execute a safe emergency landing at Houston Intercontinental Airport in Houston, Texas. All 398 passengers and crew aboard the flight survived, although six passengers and a flight attendant situated near the wing suffered minor injuries when debris punctured the fuselage. Extensive investigation by the National Transportation Safety Board determined that the cause of the engine failure was linked to stress fatigue in the number 2 fan disk that went unnoticed for 7 years following a birdstrike incident in 2001, which caused extensive damage to both port engine fan disks. Although the plane's maintenance logs indicate that both fan disks were fully repaired following the accident, in fact, only the number 1 fan disk was completely repaired, while the number 2 disk still had a microscopic crack present. Basic Details Date: 16 September, 2008 Survivors: 398 (All) Fatalities: 0 Site: In mid-air over Texas Conclusion: Catastrophic Engine Failure Aircraft Orbit Airlines Flight 112 Date: 16 September, 2008 Operator: Orbit Airlines Aircraft: Boeing 747-444 Registration: N851OR Passengers: 372 Crew: 17 Origin: McCarran International Airport, Las Vegas, Nevada, USA Destination: London Heathrow Airport, London, United Kingdom Survivors: 389 (All) Fatalities: 0 Injuries (non-fatal): 7 Aircraft and Flight Crew The aircraft involved in the incident was a 15-year-old Boeing 747-444 (registration N851OR). The aircraft was manufactured in March 1993 and was delivered to Orbit Airlines on June 29, 1993. This aircraft was the 3rd 747-400 to be delivered to Orbit Airlines; the airline had ordered the more advanced 747-400 to replace its Boeing 747-200 fleet for long-haul routes. The aircraft was powered by four General Electric CF6-80C2 turbofan engines. As of January 2008, the airframe has acquired over 32,931 flight hours. The airplane has been involved in a prior accident on March 19, 2001. While operating as Orbit Flight 37 from San Francisco to Tokyo, both the plane's port side (left) engines ingested a small flock of seagulls while on its initial climb out of SFO. The birdstrike substantially damaged both engines and forced the pilots to return to San Francisco. None of the 289 passengers and crew were harmed in the incident, the aircraft's engines were repaired, and the plane was returned to service the following month. On board Flight 112 were 38-year-old Captain Daniel Him, 42-year-old First Officer Parker Burns, Relief Captain Mike Bunbury, and Relief First Officer Tony Civar. The cabin crew consisted of 13 flight attendants. All four pilots were based at the Orbit Airlines pilot training facility in Memphis, Tennessee, and were fully trained and certified in accordance with FAA standard regulations. The captain was also an instructor pilot for the Boeing 747-400. N851OR's latest maintenance check took place on 8 August, 2008. No technical or mechanical issues were noted during this time. Accident Events Orbit Airlines Flight 112 took off from McCarran International Airport at 12:04 PM PST on 16 September, 2008, bound for London Heathrow International Airport. The flight was uneventful until around 12:58 PM, when the plane was cruising 42,000 feet (14,630 meters) above rural Texas, when the pilots heard a sharp bang coming from the port side wing of the aircraft. The bang was the result of the number 2 (the inboard left) engine's fan disk failing at high speed. This high speed failure of the disk hurled fragments of the fan's blades, at an estimated speed of about 312 mph (502 km/h), into the number 1 (the outboard) engine, causing substantial damage to the number 1 fan disk. Small pieces of the number 1 fan disk also broke free and were thrown at high speed into the underside of the wing, which punctured fuel lines for both engines. Furthermore, fragments from both engine disks penetrated the plane's fuselage, striking the windows and just above the cabin floor. This opened up a 12 x 7.3 inch hole in the plane's skin and damaged 4 of the overwing passenger windows, severely cracking three and shattering one completely, causing a rapid decompression. Six passengers (four seated in the window seats closest to the damaged windows and two in aisle seats) and one flight attendant serving these passengers at the time of the incident sustained minor injuries inflicted by flying pieces of window glass and engine parts hurled from outside. The pilots immediately suspected a catastrophic engine failure took place and shut down engines 1 and 2. The pilots also received a warning about a fire in engine 2 that extinguished itself 3 minutes later. The flight crew declared an emergency and requested to air traffic control (ATC) an emergency landing at Houston Intercontinental Airport. ATC gave the crew permission and the flight began its descent. In the cabin, the oxygen masks were dropped to the passengers and flight attendants instructed passengers on how to evacuate the aircraft. Soon, at 01:11 PM, Flight 1 12 landed safely in Millardo and all 398 passengers and crew were evacuated within 100 seconds of landing. Investigation An investigation into the incident was conducted by the National Transportation Safety Board(NTSB) with assistance from the Federal Aviation Admnistration (FAA). Orbit Airlines also conducted its own secondary investigation alongside the NTSB to provide assistance in the main investigation. Investigators initially suspected that a design flaw in the fan disk of the 747's number 2 General Electric CF6-80C2 turbofan engine was to blame. This hypothesis was brought to light after another similar accident 2 months prior that occurred on another Orbit Airlines 747 with the same power plant as the Flight 112 aircraft, in which the pilots noticed a rattling sound coming from one of the port wing engines. After inspection of that aircraft's engines, it was noted that there were numerous fatigue cracks in the fan disk of the engine in question that were possibly linked to major stress placed on the fan disk. N851OR's maintenance logs were removed and were scrutinized for information that would prove useful in determining the cause of the catastrophic loss of engine 2 in flight. It was noted that, following the 2001 birdstrike incident aboard Orbit Airlines Flight 37, both port side General Electric CF6-80C2 engines were removed from the airframe in order to repair both engine fan disks, which both sustained damage. The logs stated that both the number 1 and number 2 engine fan disks were fully repaired. However, examination of the number 2 fan disk indicated otherwise. It was stated that there was a microscopic fatigue crack originating near the center of the disk, which apparently went unnoticed. For the next 7 years afterward, this crack grew slightly bigger with each flight cycle (a cycle equals one complete takeoff and landing) placing additional stress on the cracked disk. When Orbit Flight 112 flew on September 16, the cracked fan disk was pushed to the breaking point. The crack reached the outer edge of the disk, which broke off several of the disk's fan blades. This, combined with the great amount of force that the spinning disk produced, caused small metal shrapnel to damage the 747's number 1 engine, port-side wing, and fuselage. This led the NTSB investigators to believe that the repair done to engine 2 in 2001 was performed haphazardly, and was not a design flaw, which was what investigators initially speculated it to be, and was a contributing factor in the accident, though this was not the cause of the accident. The NTSB published its official report on the accident on 5 December, 2008: "The primary cause of the catastrophic loss of engine 2 on board Orbit Airlines Flight 1 12 on September 16, 2008 was caused by fatigue cracking in the number 2 fan disk that went unnoticed for 7 years following an incomplete engine repair that was carried out on the number 2 engine after the 2001 birdstrike incident that damaged both port wing engines. The crack gradually got bigger and bigger with every flight, with additional stress being placed on the cracked disk, until it was eventually pushed to the breaking point, which caused small engine parts to break free from the fan disk and be hurled from the engine and into the plane's number 1 engine, wing, and fuselage." Aftermath At the time of the accident, 7 airlines were operating the Boeing 747-400: Orbit Airlines, Pacifica Airlines, World Travel Airways, Airwave Airlines, Quantum Airlines, Quantum Air Cargo, and Global Freightways. Following the Orbit Flight 1 12 incident, Orbit Airlines, Pacifica Airlines, and Global Freightways temporarily grounded their 747-400 fleets out of fear that this type of incident might reoccur; their 747-400s were all fitted with GE CF6-80C2 engines. (Airwave's and World Travel's 747s were all fitted with Rolls Royce RB211-524G engines, while Quantum's 747s were all fitted with Pratt and Whitney PW4156A engines.) On 4 January 2009, the NTSB and FAA both issued statements requiring that airlines operating 747-400s equipped with GE CF6-80C2 engines have their planes' engines thoroughly inspected for fatigue cracking in the fan disks. This service bulletin was originally scheduled to be released 3 weeks after the incident onboard the other Orbit aircraft, in which the original bulletin only applied for Orbit's 747-400 fleet. 17 days later, on 21 January, the NTSB ordered that inspections for airlines operating all aircraft equipped with General Electric CF6 engines be made compulsory. This order applied especially for Boeing 767, Boeing 777, Airbus A330, and McDonnell Douglas MD-11 aircraft. Inspection of these aircraft were completed within 10 days of the bulletin being issued, and no similar accidents have occurred since the Flight 112 accident or since aircraft engine inspections were completed. Fearing that an incident like Flight 112 would occur again, Orbit Airlines, Pacifica Airlines, and Global Freightways grounded their 747-400s temporarily and did not return them to service until November 2009. Following their return to service, Pacifica cited that, at the time, less people were flying on the 747s; Pacifica's 747 passenger count significantly dropped from an average count of 413 passengers to about 264 passengers between November 2009 and February 2010. Orbit Airlines discontinued the flight designation 112 for the Las Vegas-London route in January 2010 and designated the flight number for Las Vegas-London flights as 135, which is still flown by the Boeing 747-400. The Boeing 747 involved as Flight 112, N851OR, was repaired in February 2009, was once again restored to service with Orbit Airlines in June 2009, and was never again involved in another accident or incident. As of January 2017, the aircraft is still flying for Orbit Airlines, and will continue to fly in the Orbit Airlines fleet as a dedicated passenger plane for years to come. Category:Accident